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The last 7 posts

Sunday, June 4th 2017, 12:32pm

by scott.kaempfe (Guest)

I, too, wondered why everyone recommended two threaded slip adaptors bc I couldn't figure out how they would unscrew it. Your explanation was very helpful. i was going to use a manifold with union couplings for ease of taking it out in the future but from these discussions I can see the ease of POTENTIALLY taking it out in the future would be offset by risk of leaks.

One point for a newbie to digest....you said that after threading a new male thread to slip adapter on the new valve you would re-attached it to the lateral line you previously cut.

"I then attach the lateral to the new FPT/slip adapter. "

I'm assuming this lateral is now too short so do you need to then add a coupling to get he lateral line back to the right length to fit into the thread/slip fitting?

Quoted from "Lowvolumejeff" ...
2) Use MALE threaded adapters on both sides of the valve body. Less likely than female to leak, and if you ever have to remove the body, you can unscrew it without having to rebuild the whole manifold
...

I must say that I've never understood this. If you use threaded adapters on both sides of the valve, aren't they both going to be right-hand threaded? This seems to mean that you can never unscrew the valve because when you start turning to loosen on side, you'll be tightening the other side. What am I missing?

Hi everbody.

HooKooDooKu's confusion about use of threaded male adapters on each side of a FPT valve,and ease of extraction is understandable. When I have had to remove a whole valve body, I cut the downstream (lateral) pipe close to the FPT adapter as close to the valve as possible. I then unscrew the old valve from the manifold, and reapply tape and screw a new one on. I then attach the lateral to the new FPT/slip adapter. Usually in a tight working space, but very doable, and has prevented me from having to replace a whole manifold along with the other valves. Since i work with the Weathermatic Silver bullet most of the time, which doe not come in a FPT/SS option (it has FPT on each port), I have to use a MPT/SS adapter on each end.

I, too, try to avoid as many threaded connections on a mainline as possible. If I am attaching PVC to metal, I always use MPT PVC to a FPT metal joint (with 5 turns of tape). Seldom if ever have I had a leak. This includes attachments to backflow devices and PRV's when needed.

I always "bench" tighten my MPT/SS before attaching them to valves. Tape the MPT/SS adapter and hand tighten it. Then in vise give it another 1/2 to full turn using a wrench. I don't think this is the "approved" way, but I have seldom had a leak. Don't over tighten, or you can crack the valve (have only had this happen once, when I got over aggressive in tightening).

BTW, another idea someone gave me is worth passing along. How to keep soil from re-entering a valve box. Take a piece of landscape fabric or Geo-textile (I use old floating row covermatrial - AKA Remay) at least 2X2 feet, and lay it over the inplace but not yet back-filled valve box. I cut an "X" in the top about 2 inches from the edge of the valve box. Then, I stretch the fabric over the outside of the box down to where it will be below grade (and not show). It (geotextile) is very stretchble, almost elastic. Spread the "skirt" out into the your hole. Backfill over the skirt, so it (skirt) will be against the valve box and the bottom and sides of the original hole with the backfill soil on top. Hope that is clear. If not I can send pictures. Works like a charm. Also easy to dig up if necessary.

Keep digging, glueing & tightening with tape.

Jeff

PS, since this thread deals with "swivel" manifolds using "O" rings, I have been told you don't use tape on the joints with "O" rings, or they will leak.

RE: Jumbo and glue it yourself

...
2) Use MALE threaded adapters on both sides of the valve body. Less likely than female to leak, and if you ever have to remove the body, you can unscrew it without having to rebuild the whole manifold
...

I must say that I've never understood this. If you use threaded adapters on both sides of the valve, aren't they both going to be right-hand threaded? This seems to mean that you can never unscrew the valve because when you start turning to loosen on side, you'll be tightening the other side. What am I missing?

...
3) Leave room between valves, so you can unscrew the valve body. Remember if this is ever necessary, you can remove the solenoid or the whole top to obtain the necessary clearance.
...

An obvious need if you're going to allow valves to be unscrewed, but also obviously not needed if unions are to be used as your means of extracting a valve. However, I must say that from experience, unions are NOT a panacea for making parts replaceable. Because a PVC union uses rubber gaskets for sealing, the geometry of what you replace must be PERFECT. The only way I know you'll ever get that if you do replace parts is to place the unions 1st and then glue to them with them in place, because if you instead try to rebuild the pipe between the unions (including the unions) and then try to reinsert that into the system, the unions will NEVER line up exactly and you WILL have leaks.

...
Since I use FPT valves, I would have to insert a nipple between the manifold and valve. Extra parts = extra expense and potential for leaks, especially on the pressure side of the valves.
...

I too used FPT valves. I forgot that to make 4 valves fit in one meter box, this was exactly what I had to do. I tried using MPTxSlip elbows, but the MPT side was too long. I had to use FPTxSlip elbows and connect them with nipples to make the setup small enough to fit.

MAIN LINE THREADED CONNECTIONS

While drip leaks are acceptable on the lateral side of valves (where the water isn't always ON), even the slightest leak on the mainline side is unacceptable as that leak will be leaking 24/7.

Having said that, I can tell you that I absolutely detest threaded connections on mainline pipe. I could never find a way that I could reliably prevent threaded connections from leaking (using tape). What I had to do was build be sort of a test stand where I could assemble parts (such as FPT elbow to an FPT valve), place the parts in a test stand, and pressurize the pipes and see if the threaded connection leaked or not. Seems like it leaked at least 33% of the time. It didn't seem to matter how much or how little tape I used, which tape I used (white stuff, or the pink stuff designed for metal pipes), or how tight I made the connections. About a third of them leaked and I had to tear it apart and try again. However, I never found a single glued connection to ever leak. Even though you are not supposed to, there was at least one connection (I think at the backflow) that the only way I got it to stop leaking was to use a little bit of pipe dope wrapped in tape.

I'm not sure why, but I had a devil of a time making sure main-line threaded connections didn't leak.

Jumbo and glue it yourself

Hi. HooKooDooKu really answered this indirectly. The way I define manifold, is any fixture with more exit ports than enterance ports. So, we refer to ones we make ourselves, as well as the pre-fab ones as manifolds. Pre-fabs go by variousmnames, often "swivel manifolds" is used.

It seems you may be referring to the pre-fab type. forgive me if I am wrong but remember there are others who will read this thread, that the information may help.

I find that since I have plenty of pipe, fixtures, and primer and solvent, it is easier and cheaper to make my own. I can customize it as HooKooDooKu outlined, and get which ever parts I need to service with in the valve box. I too, do a lot of drip. Depending on the number and types of zones, I can configure valve, filters, pressure reducers and wiring as needed this way. The most important suggestions are

2) Use MALE threaded adapters on both sides of the valve body. Less likely than female to leak, and if you ever have to remove the body, you can unscrew it without having to rebuild the whole manifold

3) Leave room between valves, so you can unscrew the valve body. Remember if this is ever necessary, you can remove the solenoid or the whole top to obtain the necessary clearance.

That said, the answer to your question on pre-fabed manifolds, is they use a form of a union with "O" rings. They tie into your mainline with a "start", a threaded adapter. They are pre threaded and the ones I am familiar with have Female swivels to be attached to the valves (FPT swivels are a potential site for leaks in my opinion). Since I use FPT valves, I would have to insert a nipple between the manifold and valve. Extra parts = extra expense and potential for leaks, especially on the pressure side of the valves.

Two hints to save space. Feed the manifold from the mainline below the box, with a vertical brach off the mainlines "t". I use thos 3 way elbows, feeding the manifold from the end of an header. Saves 4 inches. Particularly helpful if I am using drip zone assmblies of valve, filter and pressure reducer which will fit side by side, two zones in standard box with room to spare. Make access to flush wye filters a snap. I may have pictures if anyone is interested.

Hints to make glue valve manifolds easier; tape and tighten the treaded male PVC adapter into each side of valve before gluing it to the manifold. That way your valves will be upright.

Hope that helps. Making your own is not that difficult, and saves money. Done correctly, they don't leak, and are more customizable than pre-fabed.

Sounds like I should stick with the Jumbo size box. Thanks for the help!

Back to the manifold, does this come threaded so that all I will need to do is screw in the union to the manifold or will I need to glue the union to the manifold? Will I need any specific adapters for the manifold to work with the union?

I have been able to fit four valves into a standard meter box, but it was an EXTREAMLY tight fit, required a custom built manifold, and valves that were removable via unions. And even then, the way I had to fit the valve in (not using global valves) was to attach the valves to the manifold via and upside down 'U', with PVC unions in the legs of the 'U'. And to do all that required pretty much zero strait pieces of pipe (just pieces long enough to glue various couplings together).

So we're talking the manifold consisted of 4 Tees with no space between them, the Tees face up, and immediately connected to a PVC union that immediately connected to a threaded elbow screwed into the valve, the other side of the valve required another threaded elbow immediately connected to a PVC union immediately connected to an elbow to now be level with the Tees manifold and ready to lead out into the yard.

With that setup, the box is absolutely FULL... Ok, I got one more thing in there. Even though you're not supposed to, on the valve box feeding all of my drip irrigation, I placed a single PVC pressure regulator BEFORE all the drip irrigation valves. So I go from pressure regulator to Tees manifold to 4 valves to lead to 4 drip irrigation circuits. With the values forming a set of large upside-down 'U's, I was able to place the pressure regulator inside all those 'U's, and it all fits in on standard meter box (with pipes entering and leaving UNDER the box, so you will have to close off the opening for the meter if you get a true "meter" box.

Are manifolds the best route to install valves?

This is my 3rd sprinkler installation for my personal residence, as I was figuring up the parts list and searching the website I noticed the manifolds are an option to building the header. I plan to have 3 boxes for a total of 10 zones, will the 4 port manifold work in the standard regtangle valve box or will it still require the jumbo valve box?

My second question for using a manifold is what specific fitting is needed to attach the manifold to the pvc pipe? I plan to cap off the other end. When I install the valves I would like to use unions on either end of the valves. Will I need to purchase threaded unions or will I be able to glue the union to the manifold?